Upon exemplifying the known technology of multiplexing a plurality of communication paths, thereby to configure one wide-band logical link, Multilink PPP described in Non-patent document 1, the inverse multiplexing technique over ATM described in Non-patent document 2, or the like is known as a method of multiplexing only communication paths in a ground, and further, the inverse multiplexing technology described in the Non-patent document 2 is known as a method of multiplexing wireless links. Each of these technologies provides a transfer link having a wide band exceeding a band of a single path by distributing the load between the paths.
As a method of load distributing, the weighted round robin technique of, at the moment of multiplexing the communication paths on the ground, carrying out weighting that corresponds to a velocity of each path, and circulatingly selecting a transmission path, which is described in Non-patent document 4, is widely known. However, in this method, an estimation velocity of each path has to be pre-set, which causes a problem that applying this method to multiplexing of the path including a wireless link of which a velocity or a delay frequently fluctuates gives rise to a decline in a transfer efficiency caused by a difference between the estimation velocity and the actual velocity at each time even though the average velocity of the wireless link etc. is set as an estimation velocity
As a technology of solving this problem, the load distributing technique, which envisages multiplexing of the wireless link, is described in Non-patent document 3. This technology is a technique of selecting the transmission path based upon a margin of a transmission buffer of each link, as in the case of the inverse multiplexing technique. However, this method as well is effective only when a transmission node is directly coupled to a bottleneck link, and a load of a bottleneck link can be estimated from an margin of the transmission buffer, and there exists a problem that this method is not applicable to a two-way communication because, in the path including a plurality of the links, the situation in which any node cannot be directly coupled to the bottleneck occurs.
As a load distributing technique for solving this problem, the Mobile InverseMux technology in which both nodes exchange an estimation result of the velocity and the delay of each path with each other, compare a prediction delay of each of the links with that of the other based upon its estimation result, and select the transmission path, which is described in Non-patent document 5, is known.
Non-patent document 1: RFC1990
Non-patent document 2: Langdon, Robin D., “Imuxing ATM, Bit by Bit.” Larscom white paper, 1997.
Non-patent document 3: Manabu Isomura, Naoki Imai, Kiyohito Yoshihara, and Hiroki Horiuchi, “Performance Evaluation of Inverse Multiplexing of Heterogeneous Communication Media for Mobile Router”, proceedings of FIT2004 (the 3rd Forum on Information Science and Technology), M-070, pp. 239-240 (2004).
Non-patent document 4: Cisco Systems, “Load Balancing with Cisco Express Forwarding,” Cisco Application Note, January 1998.
Non-patent document 5: T. Nakata et al., “Efficient bundling of heterogeneous radio resources for broadband Internet access from moving vehicles,” in proceedings of Global Mobile Congress 2004, Oct. 11-13, 2004, Shanghi, China.